Heterocyclic derivatives as inhibitors of factor Xa

ABSTRACT

The invention relates to heterocyclic derivatives, or pharmaceutically-acceptable salts thereof, of formula (I) wherein: A is an optionally substituted 5- or 6-membered monocyclic aromatic ring containing 1, 2 or 3 ring heteroatoms selected from oxygen, nitrogen and sulphur atoms; which possess antithrombotic and anticoagulant properties and are accordingly useful in methods of treatment of humans or animals. The invention also relates to processes for the preparation of the heterocyclic derivatives, to phaautical compositions containing them and to their use in the manufacture of medicaments for use in the production of an antithrombotic or anticoagulant effect.

This application is the National Phase of International ApplicationPCT/GB00/00354 filed Feb. 8, 2000 which designated the U.S. and thatInternational Application.

The invention relates to heterocyclic derivatives, orpharmaceutically-acceptable salts thereof, which possess antithromboticand anticoagulant properties and are accordingly useful in methods oftreatment of humans or animals. The invention also relates to processesfor the preparation of the heterocyclic derivatives, to pharmaceuticalcompositions containing them and to their use in the manufacture ofmedicaments for use in the production of an antithrombotic oranticoagulant effect.

The antithrombotic and anticoagulant effect produced by the compounds ofthe invention is believed to be attributable to their strong inhibitoryeffect against the activated coagulation protease known as Factor Xa.Factor Xa is one of a cascade of proteases involved in the complexprocess of blood coagulation. The protease known as thrombin is thefinal protease in the cascade and Factor Xa is the preceding proteasewhich cleaves prothrombin to generate thrombin.

Certain compounds are known to possess Factor Xa inhibitory propertiesand the field has been reviewed by R. B. Wallis, Current Opinion inTherapeutic Patents, 1993, 1173-1179. Thus it is known that twoproteins, one known as antistatin and the other known as tickanticoagulant protein (TAP), are specific Factor Xa inhibitors whichpossess antithrombotic properties in various animal models of thromboticdisease.

It is also known that certain non-peptidic compounds possess Factor Xainhibitory properties. Of the low molecular weight inhibitors mentionedin the review by R. B. Wallis, all possessed a strongly basic group suchas an amidinophenyl or amidinonaphthyl group.

We have now found that certain heterocyclic derivatives possess FactorXa inhibitory activity. Many of the compounds of the present inventionalso possess the advantage of being selective Factor Xa inhibitors, thatis the enzyme Factor Xa is inhibited strongly at concentrations of testcompound which do not inhibit or which inhibit to a lesser extent theenzyme thrombin which is also a member of the blood coagulationenzymatic cascade.

The compounds of the present invention possess activity in the treatmentor prevention of a variety of medical disorders where anticoagulanttherapy is indicated, for example in the treatment or prevention ofthrombotic conditions such as coronary artery and cerebro-vasculardisease. Further examples of such medical disorders include variouscardiovascular and cerebrovascular conditions such as myocardialinfarction, the formation of atherosclerotic plaques, venous or arterialthrombosis, coagulation syndromes, vascular injury including reocclusionand restenosis following angioplasty and coronary artery bypass surgery,thrombus formation after the application of blood vessel operativetechniques or after general surgery such as hip replacement surgery theintroduction of artificial heart valves or on the recirculation ofblood, cerebral infarction, cerebral thrombosis, stroke, cerebralembolism, pulmonary embolism, ischaemia and angina (including unstableangina).

The compounds of the invention are also useful as inhibitors of bloodcoagulation in an ex-vivo situation such as, for example, the storage ofwhole blood or other biological samples suspected to contain Factor Xaand in which coagulation is detrimental.

Accordingly in one aspect the present invention provides compounds ofthe formula

wherein:

A is an optionally substituted 5- or 6-membered monocyclic aromatic ringcontaining 1, 2 or 3 ring heteroatoms selected from oxygen, nifrogen andsulphur atoms;

B₁, B₂, B₃ and B₄ are independently CH or a nitrogen atom, wherein thering formed from B₁, B₂, B₃ and B₄ may optionally be substituted; withthe proviso that at least one of B₁, B₂, B₃ and B₄ is nitrogen;

T₁ is CH or N;

T₂ is CH or N; with the proviso that at least one of T₁ and T₂ is N;

X₁ is SO, SO₂, C(R₄)₂ or CO when T₁ is CH or N; or in addition X₁ is Oor S when T₁ is CH;

and wherein each R₄ is independently hydrogen or (1-4C)alkyl;

L₁ is (1-4C)alkylene or (1-3 C)alkylenecarbonyl;

R₂ is hydrogen or (1-4C)alkyl;

R₃ is hydrogen or (1-4C)alkyl;

or R₂ and R₃ are joined to form a (1-4C)alkylene or —CH₂CO— group;wherein the ring formed by T₁, R₂, R₃, T₂ and L₁ is optionallysubstituted;

X₂ is S(O)_(y) wherein y is one or two, C(R⁵)₂ or CO; and each R⁵ isindependently hydrogen or (1-4C)alkyl;

Y is selected from hydrogen, halo, trifluromethyl, trifluoromethoxy,cyano, hydroxy, amino, nitro, carboxy, carbamoyl, (1-4C)alkyl,(2-4C)alkenyl, (2-4C)alkynyl, (1-4C)alkoxy, (2-4C)alkenyloxy,(2-4C)alkynyloxy, (1-4C)alkylthio, (1-4C)alkylsulphinyl,(1-4C)alkylsulphonyl, (1-4C)alkylamino, di-(1-4C)alkylamino,(1-4C)alkoxycarbonyl,

N-(1-4C)alkylcarbamoyl, N,N-di-(1-4C)alkylcarbamoyl, (2-4C)alkanoyl,(2-4C)alkanoylamino, hydroxy-(1-4C)alkyl, (1-4C)alkoxy-(1-4C)alkyl,carboxy-(1-4C)alkyl, (1-4C)alkoxycarbonyl-(1-4C)alkyl,carbamoyl-(1-4C)alkyl, N-(1-4C)alkylcarbamoyl-(1-4C)alkyl andN,N-di-(1-4C)alkylcarbamoyl-(1-4C)alkyl;

n is 1 or 2; and

B₅ and B₆ is selected from N or CH; with the proviso that at least oneof B₅ and B₆ is N;

and pharmaceutically acceptable salts thereof.

In this specification the term “alkyl” includes both straight andbranched chain alkyl groups but references to individual alkyl groupssuch as “propyl” are specific for the straight chain version only. Ananalogous convention applies to other generic terms.

It is to be understood that certain heterocyclic derivatives of thepresent invention can exist in solvated as well as unsolvated forms suchas, for example, hydrated forms. It is to be understood that theinvention encompasses all such solvated forms which possess Factor Xainhibitory activity.

It is fuirther to be understood that, insofar as certain of thecompounds of the formula defined above may exist in optically active orracemic forms by virtue of one or more asymmetric carbon atoms, theinvention encompasses any such optically active or racemic form whichpossesses Factor Xa inhibitory activity. The synthesis of opticallyactive forms may be carried out by standard techniques of organicchemistry well known in the art, for example by synthesis from opticallyactive starting materials or by resolution of a racemic form.

Preferably A is a pyridyl, pyrimidinyl or pyridazinyl ring for example4-pyridyl, 2-pyridyl, 4-pyridazinyl, 3-pyrimidinyl, 4-pyrimidinyl or3-pyridyl. Of these 4-pyrimidinyl, 4-pyradaziiiyl and 4-pyridyl arepreferred, with 4-pyrimidinyl and 4-pyridyl most preferred.

In one aspect A is unsubstituted. In another aspect A is substituted byone, two or three atoms or groups selected from halo (for examplefluoro, chloro or bromo), trifluoromethyl, cyano, amino, oxo, hydroxy,nitro, (1-4C)alkyl (for example methyl or ethyl), (1-4C)alkoxy (forexample methoxy or ethoxy), (1-4C)alkylamino (for example methylamino orethylamino) or di-(1-4C)alkylamino (for example dimethylamino ordiethylamino). For the avoidance of doubt substituents may also be onany heteroatom.

Preferably the ring formed by B₁, B₂, B₃ and B₄ is a pyridinediyl,wherein B₁, or B₃ is a nitrogen atom, pyrimidinediyl, wherein B₁ and B₂or B₃ and B₄ are nitrogen atoms, pyridazinediyl, wherein B₁, B₃ and B₄or B₁, B₂ and B₃ are nitrogen atoms. Of these pyridinediyl andpyrimidinediyl are preferred, and pyridinediyl is most preferred.

In one aspect the ring containing B₁, B₂, B₃ and B₄ is unsubstituted. Inanother aspect the ring containing B₁, B₂, B₃ and B₄ is substituted byone or two substituents selected from hydroxy, carboxy,(1-4C)alkoxycarbonyl or one of the following;

—(CH₂)_(n)—R, —(CH₂)_(n)—NRR₁, —CO—R, —CO—NRR₁, —(CH₂)_(n)—CO—R and—(CH₂)_(n)—CO—NRR₁;

wherein n is 1 or 2;

R and R₁ are independently selected from hydrogen, (1-4C)alkyl,(2-4C)alkenyl, (2-4C)alkynyl, hydroxy(1-4C)alkyl, carboxy(1-4C)alkyl and(1-4C)alkoxycarbonyl-(1-4C)alkyl or where possible R and R₁ may togetherform a 5- or 6-membered optionally substituted heterocyclic ring whichmay include in addition to the nitrogen atom to which R and R₁ areattached 1 or 2 additional heteroatoms selected from nitrogen, oxygenand sulphur.

In a particular aspect the heterocylcic rings formed by R and R₁ arepreferably selected from pyrrolidin-1-yl, imidazolin-1-yl,piperidin-lyl, piperazin-1-yl, 4-morpholino and 4-thiomorpholino. In aparticular aspect the heterocyclic ring formed by R and R₁ may beunsubstituted. In an alternative aspect the ring formed by R and R₁ issubstituted by 1 or 2 substituents selected from oxo, hydroxy andcarboxy.

In a particular aspect, when T₁ is CH or N, X₁ is CO, SO₂, or CH₂ or,when T₁ is CH, X₁ in addition is O or S. Preferably X₁ is CO.

T₁ is CH or N and T₂ is CH or N with the proviso that at least one of T₁and T₂ is N. For the avoidance of doubt T₁ is directly attached to thegroups X₁ and L₁ and T₂ is directly attached to the groups L₁ and X₂.

L₁ is (1-4C)alkylene for example methylene. ethylene or propylene or isC₁₋₃alkylenecarbonyl for example methylenecarbonyl (—CH₂CO—), preferablyL₁ is ethylene.

In one aspect R₂ is hydrogen or (1-4C)alkyl for example methyl or ethyl.In one aspect R₃ is hydrogen or C₁₋₄alkyl for example methyl or ethyl.

In a preferred aspect R₂ and R₃ are joined to form a (1-4C)alkylenegroup, for example a methylene, ethylene or propylene group, or amethylenecarbonyl (—CH₂CO—) group, preferably ethylene.

In a particular aspect R₂ and R₃ are joined to form, together with T₁,T₂ and L₁, a heterocyclic ring wherein at least one of T₁ and T₂ is N.Examples of such heterocyclic rings are piperazine (wherein T₁ and T₂are both N), piperidine (wherein either T₁ or T₂ is N and the other isCH) and pyrrolidine (wherein either T₁ or T₂ is N and other is CH).

In one aspect the heterocyclic ring formed by T₁, T₂, L₁, R₂ and R₃ isunsubstituted. In another aspect this ring is substituted by one or twosubstituents selected from hydroxy, oxo, carboxy, (1-4C)alkoxycarbonylor one of the following;

—(CH₂)_(n)—R, —(CH₂)_(n)—NRR₁, —CO—R, —CO—NRR₁, —(CH₂)_(n)—CO—R and—(CH₂)_(n)—CO—NRR₁;

wherein n is 1 or 2;

R and R₁ are independently selected from hydrogen, (1-4C)alkyl,(2-4C)alkenyl, (2-4C)alkynyl, hydroxy(1-4C)alkyl, carboxy(1-4C)alkyl and(1-4C)alkoxycarbonyl-(1-4C)alkyl or where possible R and R₁ may togetherform a 5- or 6-membered optionally substituted heterocyclic ring whichmay include in addition to the nitrogen atom to which R and R₁ areattached 1 or 2 additional heteroatoms selected from nitrogen, oxygenand sulphur.

In a particular aspect the heterocylcic rings formed by R and R₁ arepreferably selected from pyrrolidin-1-yl, imidazolin-1-yl,piperidin-1-yl, piperazin-1-yl, 4-morpholino and 4-thiomorpholino. In aparticular aspect the heterocyclic ring formed by R and R₁ may beunsubstituted. In an alternative aspect the ring formed by R and R₁ issubstituted by 1 or 2 substituents selected from oxo, hydroxy, carboxyand (1-4C)alkyl, preferably oxo, hydroxy, and carboxy.

In a particular aspect X₂ is SO₂, CH₂ or CO. Preferably X₂ is SO₂.

In a preferred aspect Y is selected from from hydrogen, halo (bromo orchloro), trifluromethyl, trifluoromethoxy, cyano, hydroxy, amino, nitro,carboxy, carbamoyl. (1-4C)alkyl, (2-4C)alkenyl, (2-4C)alkynyl,(1-4C)alkoxy, (2-4C)alkenyloxy, (2-4C)alkynyloxy, (1-4C)alkylthio,(1-4C)alkylsulphinyl, (1-4C)alkylsulphonyl, (1-4C)alkylamino,di-(1-4C)alkylamino and (1-4C)alkoxycarbonyl.

Suitable values for substituents Y are:

for halo: fluoro, chloro, bromo;

for (1-4C)alkyl: methyl, ethyl, propyl, butyl;

for (1-4C)alkoxy: methoxy, ethoxy;

for (1-4C)alkylamino: methylamino, ethylamino;

for di-(1-4C)alkylamino: dimethylamino, diethylamino;

for (2-4C)alkenyl: vinyl and allyl;

for (2-4C)alkynyl: ethynyl and prop-2-ynyl;

for (2-4C)alkenyloxy: vinyloxy and allyloxy;

for (2-4C)alkynyloxy: ethynyloxy and prop-2-ynyloxy;

for (1-4C)alkylthio: methylthio, ethylthio and propylthio;

for (1-4C)alkylsulphinyl: methylsulphinyl, ethylsulphinyl andpropylsulphinyl;

for (1-4C)alkylsulphonyl: methylsulphonyl, ethylsulphonyl andpropylsulphonyl;

for (2-4C)alkanoylamino: acetamido, propionamido and butyramido;

for (1-4C)alkoxycarbonyl: methoxycarbonyl, ethoxycarbonyl,propoxycarbonyl and tert-butoxycarbonyl;

for N-(1-4C)alkylcarbamoyl: N-methylcarbamoyl, N-ethylcarbamoyl andN-propylcarbamoyl;

for N-di-[(1-4C)alkyl]carbamoyl: N,N-dimethylcarbamoyl,N-ethyl-N-methylcarbamoyl and N,N,-diethylcarbamoyl;

for (2-4C)alkanoyl: acetyl, propionyl and butyryl;

for hydroxy-(1-4C)alkyl: hydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyland 3-hydroxypropyl;

for(1-4C)alkoxy-(1-4C)alkyl: methoxymethyl, ethoxymethyl,1-methoxymethyl, 2-methoxyethyl, 2-ethoxyethyl and 3-methoxypropyl;

for carboxy-(1-4C)alkyl: carboxymethyl, 1-carboxyethyl, 2-carboxyethyland 3-carboxypropyl;

for (1-4C)alkoxycarbonyl-(1-4C)alkyl: methoxycarbonylmethyl,ethoxycarbonylmethyl, tert-butoxy-carbonylmethyl,1-methoxycarbonylethyl, 1-ethoxycarbonylethyl, 2-methoxycarbonylethy,2-ethoxycarbonylethyl, 3-methoxycarbonylpropyl and3-ethoxycarbonylpropyl;

for carbamoyl-(1-4C)alkyl: carbamoylmethyl, 1-carbamoylethyl,2-carbamoylethyl and 3-carbamoylpropyl;

for N-(1-4C)alkylcarbamoyl-(1-4C)alkyl: N-methylcarbamoylmethyl,N-ethylcarbamoylmethyl, N-propylcarbamoylmethyl,1-(N-methylcarbamoyl)ethyl, 1-(N-ethylcarbamoyl)ethyl,2-(N-methylcarbamoyl)ethyl, 2-(N-ethylcarbamoyl)ethyl and3-(N-methylcarbamoyl)propyl;

forN,N-di-[(1-4C)alkyl]carbamoyl-(1-4C)alkyl:N,N-dimethylcarbamoylmethyl,N-ethyl-N-methylcarbamoylmethyl, N,N-diethylcarbamoylmethyl,1-(N,N-dimethylcarbamoyl)ethyl, 1-(N,N-diethylcarbamoyl)ethyl,2-(N,N-dimethylcarbanoyl)ethyl, 2-(N,N-diethylcarbamoyl)ethyl and3-(N,N-dimethylcarbamoyl)propyl;

A preferred class of compounds of the present invention is that wherein:

A is 4-pyridyl, 4-pyrimidinyl or 4-pyridazinyl;

B_(1 to 4) is forms a pyridinediyl, pyrimidinediyl or pyridazinediyl;

X₁ is CO, SO₂ or CH₂, ideally CO;

T₁ and T₂ are both N;

L₁ is ethylene or propylene;

R₂ and R₃ are joined to form an ethylene or propylene ormethylenecarbonyl group;

wherein the heterocyclic ring formed by T₁, T₂, L₁, R₂ and R₃ isunsubstituted or is substituted;

X₁ is SO₂;

B₅ or B₆ is N:

n is 1 at the 5 position;

Y is halo, preferably bromo or chloro;

and pharmaceutically-acceptable salts thereof.

A particular compound of the invention is:

1-(5-chloroindol-2-ylsulphonyl)-4-[6-(4-pyridyl)nicotinoyl]piperazine;and

1-(5-bromoindol-2-ylsull,honyl)-4-[6-(4-pyridyl)nicotinoyl]piperazine.

Compounds of formula I, or pharmaceutically-acceptable salt thereof, maybe prepared by any process known to be applicable to the preparation ofrelated compounds. Such procedures are provided as a further feature ofthe invention and are illustrated by the following representativeprocesses in which, unless otherwise stated A, B₁, B₂, B₃, B₄, X₁, T₁,T₂, L₁, R₂, R₃, X₂, B₅, B₆, Y and n have any of the meanings definedhereinbefore wherein any functional group, for example amino,alkylamino, carboxy or hydroxy, is optionally protected by a protectinggroup which may be removed when necessary.

Necessary starting materials may be obtained by standard procedures oforganic chemistry.

According to another aspect, the present invention provides a processfor preparing a compound of formula I or a pharmaceutically acceptablesalt thereof. which comprises:

(a) For the production of compounds of the formula (I) wherein T₁ is Nand X₁ is CO, by the reaction, conveniently in the presence of asuitable base, of an amine with an acid

or with a reactive derivative of the acid.

A suitable reactive derivative of the acid is, for example, an acylhalide, an anhydride, an activated amide, an active ester, or theproduct of the reaction of the acid and a carbodiimide such asN,N′-dicyclohexylcarbodiimide orN-(3-dimethylaminopropyl)-N′-ethyl-carbodiimide.

The reaction is conveniently carried out in the presence of a suitablebase such as, for example, an alkali or alkaline earth metal carbonate,alkoxide, hydroxide or hydride, for example sodium carbonate, potassiumcarbonate, sodium ethoxide, potassium butoxide, sodium hydroxide,potassium hydroxide, sodium hydride or potassium hydride, or adialkylamino-lithium, for example lithium di-isopropylamide, or, forexample, an organic amine base such as, for example, pyridine,2,6-lutidine, collidine, 4-dimethylaminopyridine, triethylamine,morpholine or diazabicyclo[5.4.0]undec-7-ene. The reaction is alsopreferably carried out in a suitable inert solvent or diluent, forexample methylene chloride, chloroform, carbon tetrachloride,tetrahydrofuran, 1,2-dimethoxyethane, N,N-dimethylformamide,N,N-dimethylacetamide, N-methylpyrrolidin-2-one, dimethylsulphoxide oracetone, and at a temperature in the range, for example, −78° to 150°C., conveniently at or near ambient temperature.

(b) For the production of those compounds of formula I wherein T₁ is CHand X₁ is O by the reaction, conveniently in the presence of a suitablecoupling agent;

A suitable value for the displaceable group Z is, for example, ahalogeno or sulphonyloxy group, for example a fluoro, chloro, bromo,mesyloxy or 4-tolylsulphonyloxy group.

A suitable reagent for the coupling reaction when Z is a halogeno orsulphonyloxy group is, for example, a suitable base, for example, analkali or alkaline earth metal carbonate, hydroxide or hydride, forexample sodium carbonate, hydroxide or hydride, for example sodiumcarbonate, potassium carbonate, sodium hydroxide, potassium hydroxide,sodium hydride or potassium hydride. The alkylation reaction ispreferably performed in a suitable inert solvent or diluent, for exampleN,N-dimethylfornamide, N,N-dimethylacetamide, dimethylsulphoxide,acetone, 1,2-dimethoxyethane or tetrahydrofuran, and at a temperature inthe range, for example, −10° to 150° C., conveniently at or near ambienttemperature.

An analogous procedure may be employed for the preparation of thosecompounds of the formula (I) wherein T₁ is CH and X₁ is a group of theformula S.

A suitable reagent for the coupling reaction of the alcohol, wherein Zis a hydroxy group, where the hydroxy group is converted in situ to adisplaceable group as defined above, is, for example, the reagentobtained when said alcohol is reacted with a di-(1-4C)alkylazodicarboxylate in the presence of a triarylphosphine ortri-(1-4C)alkylphosphine, for example with diethyl azodicarboxylate inthe presence of triphenylphosphine or tributylphosphine. The reaction ispreferably performed in a suitable inert solvent or diluent, for exampleacetone, 1,2-dimethoxyethane or tetrahydrofuran, and at a temperature inthe range, for example, 10° to 80° C., conveniently at or near ambienttemperature.

(c) For the production of those compounds of formula (I) wherein T₁ is Nand X₁ is CH(R₄), the reductive amination of a keto compound below:

with an amine as defined in (a) above.

A suitable reducing agent is, for example, a hydride reducting agent,for example an alkali metal aluminium hydride such as lithium aluminiumhydride or, preferably, an alkali metal borohydride such as sodiumborohydride, sodium cyanoborohydride, sodium triethylborohydride, sodiumtrimethoxyborohydride and sodium triacetoxyborohydride. The reaction isconveniently performed in a suitable inert solvent or diluent, forexample tetrahydrofuran and diethyl ether for the more powerful reducingagents such as lithium aluminium hydride, and, for example, methylenechloride or a protic solvent such as methanol and ethanol for the lesspowerful reducing agents such as sodium triacetoxyborohydride. Thereaction is performed at a temperature in the range, for example, 10° to80° C., conveniently at or near ambient temperature.

(d) By the reaction of:

wherein Z is a displaceable group such as halo, with an activatedderivative of heterocyclic ring A. Suitable activated derivativesinclude metalised derivatives, such as with zinc or tin, and boranederivatives. The activated derivative of heterocyclic ring A is reactedwith the above compound to effect cross coupling where Z is a halogroup, such as iodo, bromo or chloro and triflate. Suitably the reactionis catalysed by use of a transition state metal catalyst, such aspalladium, e.g. tetrakis (triphenylphosphine) palladium(0).

Alternatively it is possible that ring A contains the displaceable groupZ and the ring containing B₁ to B₄ is activated, as described above.

The reaction is not suitable for compounds which contain halosubstituents on A, B, or L₁.

(e) By forming A ring on the above compound (d), wherein Z is afunctional group capable of cyclisation. Suitable reagents andconditions are described in Bredereck H. Chem.Ber.; 96, 1505, (1963);Fuchigami, T., Bull. Chem. Soc. Jpn., 49, p3607, (1976); Huffman, K. R.,J. Org. Chem., 28, p1812, (1963); Palusso, G., Gazz. Chim. Ital., 90,p1290, (1960) and Ainsworth C. J., Heterocycl. Chem., 3, p470, (1966).Processes suitable for synthesis of starting materials in suchcyclisation reactions are described in Zhang M. Q. et.al; J.Heterocyclic. Chem.; 28, 673, (1991) and Kosugi, M. et al., Bull. Chem.Soc. Jpn., 60, 767-768 (1987).

(f) For the production of compounds wherein T₂ is N, by the reaction:

wherein Z is a displaceable group for example chloro, under conditionssimilar to those of process variant (a) above.

(g) For the production of compounds wherein T₁ is N and X₁ is SO or SO₂,by the reaction:

wherein x is one or two and Z is a displaceable group; under appropriateconventional coupling conditions, similar to those of process variant(a) above.

(h) By coupling the heteroaryl group to T₂ with methods analogous tothose described in process variants (a), (c) and (f) for preparing theB—X₁—T₁— moiety may be employed.

(i) For the production of compounds of the formula (I) wherein X₁ is agroup of the formula SO, SO₂, wherein the ring containing B₁ to B₄ bearsa 1-oxothiomorpholino or 1,1-dioxothiomorpholino group or a substituentwhich contains a (1-4C)alkylsulphinyl, (1-4C)alkylsulphonyl,1-oxothiomorpholino or 1,1-dioxothiomorpholino group, wherein X₂ is agroup of the formula SO or SO₂. wherein Q bears a (1-4C)alkylsulphinyl,(1-4C)alkylsulphonyl. phenylsulphinyl, phenylsulphonyl,heteroarylsulphinyl or heteroarylsulphonyl group, the oxidation of thecorresponding compound of the formula I wherein X₁, X₂, or both X₁ andX₂ is S.

A suitable oxidising agent is, for example, any agent known in the artfor the oxidation of thio to sulphinyl and/or sulphonyl, for example,hydrogen peroxide, a peracid (such as 3-chloroperoxybenzoic orperoxyacetic acid), an alkali metal peroxysulphate (such as potassiumperoxymonosulphate), chromium trioxide or gaseous oxygen in the presenceof platinum. The oxidation is generally carried out under as mildconditions as possible and with the required stoichiometric amount ofoxidising agent in order to reduce the risk of over oxidation and damageto other functional groups. In general the reaction is carried out in asuitable solvent or diluent such as rnethylene chloride, chloroform,acetone, tetrahydrofuran or tert-butyl methyl ether and at atemperature, for example, at or near ambient temperature, that is in therange 15 to 35° C. Suitable reagents and conditions are described in,for example, Page G. O.; Synth. Commun. 23, (1993) 6, 765-769. When acompound carrying a sulphinyl group is required a milder oxidising agentmay also be used, for example sodium or potassium metaperiodate,conveniently in a polar solvent such as acetic acid or ethanol. It willbe appreciated that when a compound of the formula I containing asulphonyl group is required, it may be obtained by oxidation of thecorresponding sulphinyl compound as well as of the corresponding thiocompound. Those compounds of formula I which contain oxygen labilegroups (such as A ring is pyridyl) are probably not suitableintermediates for this process step, unless oxidation of such groups isdesired.

When a pharmaceutically-acceptable salt of a compound of the formula Iis required, it may be obtained, for example, by reaction of saidcompound with a suitable acid or base using a conventional procedure.

When an optically active form of a compound of the formula I isrequired, it may be obtained, for example, by carrying out one of theaforesaid procedures using an optically active starting material or byresolution of a racemic form of said compound using a conventionalprocedure, for example by the formation of diastereomeric salts, use ofchromatographic techniques, conversion using chirally specific enzymaticprocesses, or by additon of temporary extra chiral group to aidseperation.

As stated previously, the compounds of the formula I are inhibitors ofthe enzyme Factor Xa. The effects of this inhibition may be demonstratedusing one or more of the standard procedures set out hereinafter:

a) Measurement of Factor Xa Inhibition

An in vitro assay system is carried out based on the method of Kettneret al., J. Biol. Chem., 1990, 265, 18289-18297, whereby variousconcentrations of a test compound are dissolved in a pH7.5 buffercontaining 0.5% of a polyethylene glycol (PEG 6000) and incubated at 37°C. with human Factor Xa (0.001 Units/ml., 0.3 ml) for 15 minutes. Thechromogenic substrate S-2765 (KabiVitrum AB, 20 μM) is added and themixture is incubated at 37° C. for 20 minutes whilst the absorbance at405 nm is measured. The maximum reaction velocity (Vmax) is determinedand compared with that of a control sample containing no test compound.Inhibitor potency is expressed as an IC₅₀ value.

b) Measurement of Thrombin Inhibition

The procedure of method a) is repeated except that human thrombin (0.005Units/ml) and the chromogenic substrate S-2238 (KabiVitrum AB, 7 μM) areemployed.

c) Measurement of Anticoagulant Activity

An in vitro assay whereby human, rat or rabbit venous blood is collectedand added directly to a sodium citrate solution (3.2 g/100 ml, 9 partsblood to 1 part citrate solution). Blood plasma is prepared bycentrifugation (1000 g. 15 minutes) and stored at 24° C. Conventionalprothrombin time (PT) tests are carried out in the presence of variousconcentrations of a test compound and the concentration of test compoundrequired to double the clotting time, hereinafter referred to as CT2, isdetermined. In the PT test, the test compound and blood plasma areincubated at 37° C. for 10 minutes. Tissue thromboplastin with calcium(Sigma Limited, Poole, England) is added and fibrin formation and thetime required for a clot to form are determined.

d) An ex vivo Assay of Anticoagulant Activity

The test compound is administered intravenously or orally to a group ofAlderley Park Wistar rats. At various times thereafter animals areanaesthetised, blood is collected and PT coagulation assays analogous tothose described hereinbefore are conducted.

e) An in vivo Measurement of Antithrombotic Activity

Thrombus formation is induced using an analogous method to thatdescribed by Vogel et al., Thromb. Research, 1989, 54, 399-410. A groupof Alderley Park Wistar rats is anaesthetised and surgery is performedto expose the vena cava. Collateral veins are ligated and two loosesutures are located, 0.7 cm apart, round the inferior vena cava. Testcompound is administered intravenously or orally. At an appropriate timethereafter tissue thromboplastin (30 μl/kg) is administered via thejugular vein and, after 10 seconds, the two sutures are tightened toinduce stasis within the ligated portion of vena cava. After 10 minutesthe ligated tissue is excised anid the thrombus therein is isolated,blotted and weighed.

(f) Rat Disseminated Intravascular Coagulation in vivo Activity Test

Fasted male Alderley Park rats (300-450 g) are pre-dosed by oral gavage(5 mls/kg) with compound or vehicle (5% DMSO/PEG200) at various timesbefore being anaesthetised with Intraval® (120 mg/kg i.p.). The leftjugular vein and the right carotid artery are exposed and cannulated. A1 mL blood sample is taken from the carotid canular into 3.2% trisodiumcitrate. 0.5 mL of the whole blood is then treated with EDTA and usedfor platelet count determination whilst the remainder is centrifuged (5mins, 20000 g) and the resultant plasma frozen for subsequent druglevel, fibrinogen or thrombin antithrombin (TAT) complex determinations.Recombinant human tissue factor (Dade Innovin Cat.B4212-50),reconstituted to the manufacturers specification, is infused (2mL/kg/hr) into the venous canular for 60 minutes. Immediately after theinfusion is stopped a 2 mL blood sample is taken and platelet count,drug level, plasma fibrinogen concentration and TAT complex aredetermined as before. Platelet counting is performed using at CoulterT540 blood analyser. Plasma fibrinogen and TAT levels are derterminingusing a clotting assay (Sigma Cat.880-B) and TAT ELISA (Behring)respectively. The plasma concentration of the compound is bioassayedusing human Factor Xa and a chromogenic substrate S2765 (Kabi),extrapolated from a standard curve (Fragmin) and expressed inAnti-Factor Xa units. The data is analysed as follows; tissuefactor-induced reductions in platelet count are normalised with respectto pre-dose platelet count and drug activity expressed as a percentinhibition of tissue factorinduced thrombocytopenia when compared tovehicle treated animals. Compounds are active if there is statisticallysignificant (p<0.05) inhibition of TF-induced thrombocytopenia.

Example had an IC₅₀ (Factor Xa) of 0.007 μM as measured in test a)

According to a further feature of the invention there is provided apharmaceutical composition which comprises a heterocyclic derivative ofthe formula 1, or a pharmaceutically-acceptable salt thereof, inassociation with a pharmaceutically-acceptable diluent or carrier.

The composition may be in a form suitable for oral use, for example atablet, capsule, aqueous or oily solution, suspension or emulsion; fortopical use, for example a cream, ointment, gel or aqueous or oilysolution or suspension; for nasal use, for example a snuff, nasal sprayor nasal drops; for vaginal or rectal use, for example a suppository;for administration by inhalation, for example as a finely divided powdersuch as a dry powder, a microcrystalline form or a liquid aerosol; forsub-lingual or buccal use, for example a tablet or capsule; or forparenteral use (including intravenous, subcutaneous, intramuscular,intravascular or infusion), for example a sterile aqueous or oilysolution or suspension. In general the above compositions may beprepared in a conventional manner using conventional excipients.

The amount of active ingredient (that is a heterocyclic derivative ofthe formula 1, or a pharrnaceutically-acceptable salt thereof) that iscombined with one or more excipients to produce a single dosage formwill necessarily vary depending upon the host treated and the particularroute of administration. For example, a formulation intended for oraladministration to humans will generally contain, for example, from 0.5mg to 2 g of active agent compounded with an appropriate and convenientamount of excipients which may vary from about 5 to about 98 percent byweight of the total composition. Dosage unit forms will generallycontain about 1 mg to about 500 mg of an active ingredient.

According to a further feature of the invention there is provided use ofa heterocyclic derivative of the formula I, or apharmaceutically-acceptable salt thereof, in the manufacture of amedicament for use in a method of treatment of the human or animal bodyby therapy.

The invention also includes the use of such an active ingredient in theproduction of a medicament for use in:

(i) producing a Factor Xa inhibitory effect;

(ii) producing an anticoagulant effect;

(iii) producing an antithrombotic effect;

(iv) treating a Factor Xa mediated disease or medical condition;

(v) treating a thrombosis mediated disease or medical condition;

(vi) treating coagulation disorders; and/or

(vii) treating thrombosis or embolism involving Factor Xa mediatedcoagulation.

The invention also includes a method of producing an effect as definedhereinbefore or treating a disease or disorder as defined hereinbeforewhich comprises administering to a warm-blooded animal requiring suchtreatment an effective amount of an active ingredient as definedhereinbefore.

The size of the dose for therapeutic or prophylactic purposes of acompound of the formula I will naturally vary according to the natureand severity of the medical condition, the age and sex of the animal orpatient being treated and the route of administration; according to wellknown principles of medicine. As mentioned above, compounds of theformula I are useful in the treatment or prevention of a variety ofmedical disorders where anticoagulant therapy is indicated. In using acompound of the formula I for such a purpose, it will generally beadministered so that a daily dose in the range, for example, 0.5 to 500mg/kg body weight is received, given if required in divided doses. Ingeneral lower doses will be administered when a parenteral route isemployed, for example a dose for intravenous administration in therange, for exanple, 0.5 to 50 mg/kg body weight will generally be used.For preferred and especially preferred compounds of the invention, ingeneral, lower doses will be employed, for example a daily dose in therange, for example, 0.5 to 10 mg/kg body weight.

Although the compounds of the formula I are primarily of value astherapeutic or prophylactic agents for use in warm-blooded animalsincluding man, they are also useful whenever it is required to producean anticoagulant effect, for example during the ex-vivo storage of wholeblood or in the development of biological tests for compounds havingnticoagulant properties.

The compounds of the invention may be administered as a sole therapy orthey may be administered in conjunction with other pharmacologicallyactive agents such as a thrombolytic agent, for example tissueplasminogen activator or derivatives thereof or streptokinase. Thecompounds of the invention may also be administered with, for example, aknown platelet aggregation inhibitor (for example aspirin, a thromboxaneantagonist or a thromboxane synthase inhibitor), a known hypolipidaemicagent or a known anti-hypertensive agent.

The invention will now be illustrated in the following Examples inwhich, unless otherwise stated:

(i) evaporations were carried out by rotary evaporation in vacuo andwork-up procedures were carried out after removal of residual solids byfiltration;

(ii) operations were carried out at room temperature, that is in therange 18-25° C. and under an atmosphere of an inert gas such as argon;

(iii) the end-products of the formula I have satisfactory microanalysesand their structures were confirmed by nuclear magnetic resonance (NMR)and mass spectral techniques. Chemical shift values were measured on thedelta scale; the following abbreviations have been used: s, singlet; d,doublet; t, triplet; q, quartet; m, multiplet;

(iv) intermediates were not generally fully characterised and purity wasassessed by thin layer chromatographic, infra-red (IR) or NMR analysis;and

(v) melting points were determined using a Mettler SP62 automaticmelting point apparatus or an oil oath apparatus; melting points for theend-products of the formula I were generally determined aftercrystallisation from a conventional organic solvent such as ethanol,methanol, acetone, ether or hexane, alone or in admixture.

EXAMPLE 11-(5-Chloroindol-2-ylsulphonyl)-4-[6-(4-pyridyl)nicotinoyl]piperazine

A stirred suspension of 6-(4-pyridyl)nicotinic acid (400 mg, 2 mmol) indimethylformamide, DMF, (10 ml) was treated with1-(5-chloroindol-2-ylsulphonyl)piperazine (600 mg, 2 mmol, 1 mol eq.)and 1-(3-dimethylaminopropyl)-3-ethylcarbodi-imide hydrochloride (EDAC,460 mg, 2.4 mmol, 1.2 mol eq.). After stirring overnight the solvent wasremoved in vacuo and the residue chromatographed (Isolute 20 g silicacartridge, eluting with dichloromethane containing 2.5%-5% v/v ofmethanol) to yield1-(5-chloroindol-2-ylsulphonyl)-4-[6-(4-pyridyl)nicotinoyl]piperazine asa colourless foam (680 mg). This was dissolved indichloromethane/methanol mixture (40 ml of 1:1) and treated with asaturated solution of HCI in methanol until acid to indicator paper(slight excess). The resulting solution of hydrochloride salt wasevaporated to dryness and the residue boiled in 2-propanol (100 ml,incomplete solution). Filtration and cooling gave1-(5-chloroindol-2-ylsulphonyl)-4-[6-(4-pyridyl)nicotinoyl]piperazinehydrochloride as a colourless solid, (220 mg), ¹H NMR (d₆-DMSO) 3.0-3.3(broad d, 4H), 3.6-4.0 (broad d, 4H), 7.05 (s, 1H), 7.35 (dd, 1H), 7.5(d, 1H), 7.8 (d, 1H), 8.1 (dd, 1H), 8.35 (d, 1H), 8.5 (m, 2H), 8.8 (d,1H), 8.95 (d, 2H), 12.4 (s, 1H), signals were also present due to2-propanol (0.5 mol equiv.); MS (M+H)⁺ 481/483; mp 186-190° C. (notsharp).

The requisite 64-pyridyl)nicotinic acid starting material was preparedas follows:

A solution of1-[6-(4-pyridyl)-3-pyridyl]-4-(tert.-butyloxycarboryl)-piperazine (3.7g, 10 mnuol) and potassium carbonate (6.9 g, 50 mmol) in methanol/wate,(90 m1 of a 2:1 mixture) (30 ml) was heated vat reflux for 7 hrs. It wasthen cooled and neutralised with dilute HCI (50 ml of 2M), and some ofthe solvent removed in vacuo. More water was added and the resultantslurry left to stand for 2 hrs. Filtration, washing with water anddrying gave the above starting material (870 mg) which was used withoutfurther purification, ¹H NMR (d₆-DMSO), 8.1 (d, 2H), 8.25 (d, 1H), 8.45(dd, 1H), 8.75 (d, 2H), 9.2 (d, 1H), MS (M+H)⁺201, (M−H)⁻199.

1-[6-(4-Pyridyl)-3-pyridyl]-4-(tert.-butyloxycarbonyl)-piperazine wasprepared as shown in Example 1 of PCT/GB98/02210.

1-(5-Chloroindol-2-ylsulphonyl)piperazine was prepared as shown inExample 3 of GB9809351.1.

EXAMPLE 21-(5-Bromoindol-2-ylsulphonyl)-4-[6-(4-pyridyl)nicotinoyl]piperazine

By an exactly analogous method to that in Example 1, starting from6-(4-pyridyl)nicotinic acid (400 mg, 2 mmol) and1-(5-bromoindol-2-ylsulphonyl)piperazine (700 mg, 2 mmol, 1 mol eq.),was prepared1-(5-bromoindol-2-ylsulphonyl)-4-[6-(4-pyridyl)nicotinoyl]piperazinefree base, as a colourless solid, (540 mg), ¹H NMR (d₆-DMSO) 3.0-3.3(broad d, 4H), 3.4-3.9 (broad d, 4H), 7.0 (s, 1H), 7.45 (s, 2H), 7.95(s, 1H), 8.0 (d, 1H), 8.1 (dd, 2H), 8.15 (d, 1H), 8.75 (m, 3H), 12.4 (s,1H), signals were also present due to DMF (1 mol equiv.); MS(M+H)⁺526/528.

The requisite 1-(5-bromoindol-2-ylsulphonyl)piperazine starting materialwas prepared in a manner analogous to that for the corresponding5-chloro compound.

What is claimed is:
 1. A compound of the formula I

wherein: A is a 5- or 6-membered monocyclic aromatic ring containing 1,2 or 3 ring heteroatoms selected from oxygen, nitrogen and sulphuratoms, optionally substituted by one, two or three atoms or groupsselected from halo, trifluoromethyl, cyano, amino, oxo, hydroxy, nitro,(1-4C)alkyl, (1-4C)alkoxy, (1-4C)alkylamino or di-(1-4C)alkylamino; B₁,B₂, B₃ and B₄ are independently CH or a nitrogen atom, with the provisothat at least one of B₁, B₂, B₃ and B₄ is nitrogen; wherein the ringformed from B₁, B₂, B₃ and B₄ may optionally be substituted by one ortwo substituents selected from hydroxy, carboxy, (1-4C)alkoxycarbonyl orone of the following; —(CH₂)_(m)—R, —(CH₂)_(m)—NRR₁, —CO—R,—CO—NRR₁,—(CH₂)—CO—R and —(CH₂)_(m)—CO—NRR₁; wherein m is 1 or 2; R and R₁ areindependently selected from hydrogen, (1-4C)alkyl, (2-4C)alkenyl,(2-4C)alkynyl, hydroxy(1-4C)alkyl, carboxy(1-4C)alkyl and(1-4C)alkoxycarbonyl-(1-4C)alkyl or R and R₁ may together form a 5- or6-membered optionally substituted heterocyclic ring which may include inaddition to the nitrogen atom to which R and R₁ are attached 1 or 2additional heteroatoms selected from nitrogen, oxygen and sulphur; X₁ isCO, SO₂, or CH₂; R₂ and R₃ are ioined to form an ethylene group to form,together with T₁, T₂ and L₁ a piperazine ring, which is unsubstituted oris substituted by one or two substituents independently selected fromhydroxy, oxo, carboxy, (1-4C)alkoxycarbonyl or one of the following;—(CH₂)_(p)—R, —(CH₂)_(p)—NRR₁, —CO—R, —CO—NRR₁; —(CH₂)_(p)—CO—R and—(CH₂)_(p)—CO—NRR₁; wherein n is 1 or 2; R and R₁ are independently asdefined above, Y is selected from hydrogen, halo, trifluromethyl,trifluoromethoxy, cyano, hydroxy, amino, nitro, carboxy, carbamoyl,(1-4C)alkyl, (2-4C)alkenyl, (2-4C)alkynyl, (1-4C)alkoxy,(2-4C)alkenyloxy, (2-4C)alkynyloxy, (1-4C)alkylthio,(1-4C)alkylsulphinyl, (1-4C)alkylsulphonyl, (1-4C)alkylamino,di-(1-4C)alkylamino, (1-4C)alkoxycarbonyl, N-(1-4C)alkylcarbamoyl,N,N-di-(1-4C)alkylcarbamoyl, (2-4C)alkanoyl, (2-4C)alkanoylamino,hydroxy-(1-4C)alkyl, (1-4C)alkoxy-(1-4C)alkyl, carboxy-(1-4C)alkyl,(1-4C)alkoxycarbonyl-(1-4C)alkyl, carbamoyl-(1-4C)alkyl,N-(1-4C)alkylcarbamoyl-(1-4C)alkyl andN,N-di-(1-4C)alkylcarbamoyl-(1-4C)alkyl; n is 1 or 2; and one of B₅ andB₆ is N and the other is CH; or a pharmaceutically acceptable saltthereof.
 2. A compound of the formula I as claimed in claim 1 wherein Ais a pyridyl, pyrimidinyl or pyridazinyl ring.
 3. A compound of theformula I as claimed in claim 2 wherein A is 4-pyridyl, 2-pyridyl,4-pyridazinyl, 3-pyrimidinyl, 4-pyrimidinyl or 3-pyridyl.
 4. A compoundof the formula I as claimed in claim 1 wherein A is unsubstituted or issubstituted by one,m two or three atoms or groups selected from fluoro,chloro or bromo, trifluoromethyl, cyano, amino, oxo, hydroxy, nitro,methyl or ethyl, methoxy or ethoxy, methylamino, ethylamino,dimethylamino and diethylamino.
 5. A compound of the formula I asclaimed in claim 1, wherein the ring formed by B₁, B₂, B₃ and B₄ is apyridinediyl, wherein B₁, or B₃ is a nitrogen atom, pyrimidinediyl,wherein B₁ and B₂ or B₃ and B₄ are nitrogen atoms or a ring, wherein B₁,B₃ and B₄ or B₁, B₂ and B₃ are nitrogen atoms.
 6. A compound of theformula I as claimed in claim 1, wherein the ring containing B₁, B₂, B₃and B₄ is unsubstituted.
 7. A compound of the formula I as claimed inclaim 1, wherein the heterocylcic ring formed by R and R₁ is selectedfrom pyrrolidin-1-yl, imidazolin-1-yl, piperidin-1yl, piperazin-1-yl,4-morpholino and 4-thiomorpholino.
 8. A compound of the formula I asclaimed in claim 1, wherein the heterocyclic ring formed by R and R₁ isunsubstituted or the ring formed by R and R₁ is substituted by 1 or 2substituents selected from oxo, hydroxy and carboxy.
 9. A compound ofthe formula I as claimed in claim 1, wherein Y is selected fromhydrogen, halo, trifluromethyl, trifluoromethoxy, cyano, hydroxy, amino,nitro, carboxy, carbamoyl, (1-4C)alkyl, (2-4C)alkenyl, (2-4C)alkynyl,(1-4C)alkoxy, (2-4C)alkenyloxy, (2-4C)alkynyloxy, (1-4C)alkylthio,(1-4C)alkylsulphinyl, (1-4C)alkylsulphonyl, (1-4C)alkylamino,di-(1-4C)alkylamino and (1-4C)alkoxycarbonyl.
 10. A compound of formula(I) as defined in claim 1 wherein A is 4-pyridyl, 4-pyrimidinyl or4-pyridazinyl; the ring containing B_(1 to 4) forms a pyridinediyl,pyrimidinediyl or pyridazinediyl ring; X₁ is CO; n is 1 at the 5position; and Y is halo or a pharmaceutically-acceptable salt thereof.11. A compound according to claim 10 wherein Y is chloro or bromo.
 12. Apharmaceutical composition which comprises a compound of the formula I,as defined in any one of claims 1 to 8 and 9 or apharmaceutically-acceptable salt thereof, in association with apharmaceutically-acceptable diluent or carrier.
 13. A method forproducing a Factor Xa inhibitory effect, said method comprisingadministering to a warm-blooded animal in need thereof aninhibition-effective amount of a compound of formula I as defined in anyone of claims 1 to 8 and 9 or a pharmaceutically-acceptable saltthereof.